/* ========================================================================
 * JCommon : a free general purpose class library for the Java(tm) platform
 * ========================================================================
 *
 * (C) Copyright 2000-2004, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jcommon/index.html
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * -------------------------------------
 * AbstractElementDefinitionHandler.java
 * -------------------------------------
 * (C)opyright 2003, by Thomas Morgner and Contributors.
 *
 * Original Author:  Kevin Kelley <kelley@ruralnet.net> -
 *                   30718 Rd. 28, La Junta, CO, 81050  USA.                                                         //
 *
 * $Id: Base64.java,v 1.5 2004/01/01 23:59:29 mungady Exp $
 *
 * Changes
 * -------------------------
 * 23.09.2003 : Initial version
 *
 */
package work.qizhi.down.encryption;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.CharArrayWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;

/**
 * Provides encoding of raw bytes to base64-encoded characters, and decoding of
 * base64 characters to raw bytes. date: 06 August 1998 modified: 14 February
 * 2000 modified: 22 September 2000
 *
 * @author Kevin Kelley (kelley@ruralnet.net)
 * @version 1.3
 */
public class Base64
{

    /**
     * returns an array of base64-encoded characters to represent the passed
     * data array.
     *
     * @param data
     *            the array of bytes to encode
     * @return base64-coded character array.
     */
    public static char[] encode(byte[] data)
    {
        char[] out = new char[((data.length + 2) / 3) * 4];

        //
        // 3 bytes encode to 4 chars. Output is always an even
        // multiple of 4 characters.
        //
        for (int i = 0, index = 0; i < data.length; i += 3, index += 4)
        {
            boolean quad = false;
            boolean trip = false;

            int val = (0xFF & data[i]);
            val <<= 8;
            if ((i + 1) < data.length)
            {
                val |= (0xFF & data[i + 1]);
                trip = true;
            }
            val <<= 8;
            if ((i + 2) < data.length)
            {
                val |= (0xFF & data[i + 2]);
                quad = true;
            }
            out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 1] = alphabet[val & 0x3F];
            val >>= 6;
            out[index + 0] = alphabet[val & 0x3F];
        }
        return out;
    }

    /**
     * Decodes a BASE-64 encoded stream to recover the original data. White
     * space before and after will be trimmed away, but no other manipulation of
     * the input will be performed.
     *
     * As of version 1.2 this method will properly handle input containing junk
     * characters (newlines and the like) rather than throwing an error. It does
     * this by pre-parsing the input and generating from that a count of VALID
     * input characters.
     **/
    public static byte[] decode(char[] data)
    {
        // as our input could contain non-BASE64 data (newlines,
        // whitespace of any sort, whatever) we must first adjust
        // our count of USABLE data so that...
        // (a) we don't misallocate the output array, and
        // (b) think that we miscalculated our data length
        // just because of extraneous throw-away junk

        int tempLen = data.length;
        for (int ix = 0; ix < data.length; ix++)
        {
            if ((data[ix] > 255) || codes[data[ix]] < 0)
                --tempLen; // ignore non-valid chars and padding
        }
        // calculate required length:
        // -- 3 bytes for every 4 valid base64 chars
        // -- plus 2 bytes if there are 3 extra base64 chars,
        // or plus 1 byte if there are 2 extra.

        int len = (tempLen / 4) * 3;
        if ((tempLen % 4) == 3)
            len += 2;
        if ((tempLen % 4) == 2)
            len += 1;

        byte[] out = new byte[len];

        int shift = 0; // # of excess bits stored in accum
        int accum = 0; // excess bits
        int index = 0;

        // we now go through the entire array (NOT using the 'tempLen' value)
        for (int ix = 0; ix < data.length; ix++)
        {
            int value = (data[ix] > 255) ? -1 : codes[data[ix]];

            if (value >= 0)// skip over non-code
            {
                accum <<= 6; // bits shift up by 6 each time thru
                shift += 6; // loop, with new bits being put in
                accum |= value; // at the bottom.
                if (shift >= 8)// whenever there are 8 or more shifted in,
                {
                    shift -= 8; // write them out (from the top, leaving any
                    out[index++] = // excess at the bottom for next iteration.
                    (byte) ((accum >> shift) & 0xff);
                }
            }
            // we will also have skipped processing a padding null byte ('=')
            // here;
            // these are used ONLY for padding to an even length and do not
            // legally
            // occur as encoded data. for this reason we can ignore the fact
            // that
            // no index++ operation occurs in that special case: the out[] array
            // is
            // initialized to all-zero bytes to start with and that works to our
            // advantage in this combination.
        }

        // if there is STILL something wrong we just have to throw up now!
        if (index != out.length)
        {
            throw new Error("Miscalculated data length (wrote " + index
                    + " instead of " + out.length + ")");
        }

        return out;
    }

    //
    // code characters for values 0..63
    //
    private static char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
            .toCharArray();

    //
    // lookup table for converting base64 characters to value in range 0..63
    //
    private static byte[] codes = new byte[256];

    static
    {
        for (int i = 0; i < 256; i++)
            codes[i] = -1;
        for (int i = 'A'; i <= 'Z'; i++)
            codes[i] = (byte) (i - 'A');
        for (int i = 'a'; i <= 'z'; i++)
            codes[i] = (byte) (26 + i - 'a');
        for (int i = '0'; i <= '9'; i++)
            codes[i] = (byte) (52 + i - '0');
        codes['+'] = 62;
        codes['/'] = 63;
    }

    // /////////////////////////////////////////////////
    // remainder (main method and helper functions) is
    // for testing purposes only, feel free to clip it.
    // /////////////////////////////////////////////////

    public static void main(String[] args)
    {
        boolean decode = false;

        if (args.length == 0)
        {
            System.out.println("usage:  java Base64 [-d[ecode]] filename");
            System.exit(0);
        }
        for (int i = 0; i < args.length; i++)
        {
            if ("-decode".equalsIgnoreCase(args[i]))
                decode = true;
            else if ("-d".equalsIgnoreCase(args[i]))
                decode = true;
        }

        String filename = args[args.length - 1];
        File file = new File(filename);
        if (!file.exists())
        {
            System.out
                    .println("Error:  file '" + filename + "' doesn't exist!");
            System.exit(0);
        }

        if (decode)
        {
            char[] encoded = readChars(file);
            byte[] decoded = decode(encoded);
            writeBytes(file, decoded);
        }
        else
        {
            byte[] decoded = readBytes(file);
            char[] encoded = encode(decoded);
            writeChars(file, encoded);
        }
    }

    private static byte[] readBytes(File file)
    {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try
        {
            InputStream fis = new FileInputStream(file);
            InputStream is = new BufferedInputStream(fis);
            int count = 0;
            byte[] buf = new byte[16384];
            while ((count = is.read(buf)) != -1)
            {
                if (count > 0)
                    baos.write(buf, 0, count);
            }
            is.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }

        return baos.toByteArray();
    }

    private static char[] readChars(File file)
    {
        CharArrayWriter caw = new CharArrayWriter();
        try
        {
            Reader fr = new FileReader(file);
            Reader in = new BufferedReader(fr);
            int count = 0;
            char[] buf = new char[16384];
            while ((count = in.read(buf)) != -1)
            {
                if (count > 0)
                    caw.write(buf, 0, count);
            }
            in.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }

        return caw.toCharArray();
    }

    private static void writeBytes(File file, byte[] data)
    {
        try
        {
            OutputStream fos = new FileOutputStream(file);
            OutputStream os = new BufferedOutputStream(fos);
            os.write(data);
            os.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }

    private static void writeChars(File file, char[] data)
    {
        try
        {
            Writer fos = new FileWriter(file);
            Writer os = new BufferedWriter(fos);
            os.write(data);
            os.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
    // /////////////////////////////////////////////////
    // end of test code.
    // /////////////////////////////////////////////////

}